How should I handle multiple file uploads in ASP.NET MVC 3?

Use Jquery file upload pluging.

I usually use plupload.

http://www.plupload.com/

My Sample To Use PlUpload:

in View:

<div id="file-upload-continer">
    <div id="btnInsertFile" style="display: inline-block; width: 100px; border: 1px solid gray;">Choose File</div>
</div>

<table class="file-upload-box">
<tr>
     <th>Title</th><th></th><th></th>
</tr>
</table>

<script type="text/javascript">
$(function () {
    var uploader = new plupload.Uploader({
        url: '@Url.Action("Upload")',
        multipart : true,
        multipart_params: { },
        runtimes: 'html5,html4',
        container: 'file-upload-continer',
        button_browse_hover : true,
        browse_button: 'btnInsertFile'
    });

    uploader.bind('Init', function (up, params) {
        $('.select-document, .file-upload-box').removeClass("hidden");
        $('.upload-support').addClass("hidden");
    });

    uploader.init();

    uploader.bind('FilesAdded', function (up, files) {
        $.each(files, function (i, file) {
            var newRow = 
                "<tr class='file-row' id='" + file.id + "'>" +
                    "<td class='title'>" + file.name + " (" + formatFileSize(file.size) + ") </td>" +
                    "<td class='cancel' id='cancel" + file.id + "'></td>" +
                    "<td class='status' id='cancel" + file.id + "'></td>" +
                "</tr>";

            $('.file-upload-box').append(newRow);

            //Bind cancel click event
            $('#cancel'+file.id).click(function(){
                $('#' + file.id).remove();
                uploader.removeFile(file);
                $(this).unbind().remove();
            });                 

        });

        uploader.start();
    });

    uploader.bind('BeforeUpload', function (up, file) {
        $(".status", ".file-row#" + file.id).addClass('throbber');
    });

    uploader.bind('FileUploaded', function (up, file) {
        $(".throbber", ".file-row#" + file.id).addClass('success').removeClass('throbber');
        $(".cancel", ".file-row#" + file.id).removeClass('cancel');
    });

    uploader.bind('Error', function (up, err) {
            $(".throbber", ".file-row#" + err.file.id).addClass('error').removeClass('throbber');
            $(".cancel", ".file-row#" + err.file.id).removeClass('cancel');
    });

});

</script>

and in My Controller:

public ActionResult Upload(string name = "", int chunk = 0)
{
    if (Request.Files.Count < 1)
        return Json(false);

    HttpPostedFileBase fileUpload = Request.Files[0];

    // Save file

    return Json(true, "text/html");
}

If you would like to use jQuery to upload your files, i will recommend you this library:

http://www.uploadify.com/

It can upload multiple files asynchronusly. There are enough examples on their website.

http://www.uploadify.com/demos/